.outer{
    width: 500px;
    height: 300px;
    background: green;
    margin: 0 auto;
    overflow: hidden;
}
.sliderimg{
    position: relative;
    width: 3120px;
    list-style: none;
    height: 333px;
    margin: 0 auto;
    background: red;
    padding-left: 0;
    left: 0px;
}
.imgtag{
    width: 500px;
    height: 300px;
    background: gray;
    float: left;
    
}
.img{
    width: 500px;
    height: 300px;
}